Ionic liquid mediated stereoselective synthesis of alanine linked hybrid quinazoline-4(3H)-one derivatives perturbing the malarial reductase activity in folate pathway

Design and synthesis of new quinazolinone derivatives: investigation of antimicrobial and biofilm inhibition effects

New quinazolin-4-ones 9-32 were synthesized in an attempt to overcome the life-threatening antibiotic resistance phenomenon. The antimicrobial screening revealed that compounds 9, 15, 16, 18, 19, 20 and 29 are the most broad spectrum antimicrobial agents in this study with safe profile on human cell lines. Additionally, compounds 19 and 20 inhibited biofilm formation in Pseudomonas aeruginosa, which is regulated by quorum sensing system, at sub-minimum inhibitory concentrations (sub-MICs) with IC50 values 3.55 and 6.86 µM, respectively. By assessing other pseudomonal virulence factors suppression, it was found that compound 20 decreased cell surface hydrophobicity compromising bacterial cells adhesion, while both compounds 19 and 20 curtailed the exopolysaccharide production which constitutes the major component of the matrix binding biofilm components together. Also, at sub-MICs Pseudomonas cells twitching motility was impeded by compounds 19 and 20, a trait which augments the cells pathogenicity and invasion potential. Molecular docking study was performed to further evaluate the binding mode of candidates 19 and 20 as inhibitors of P. aeruginosa quorum sensing transcriptional regulator PqsR. The achieved results demonstrate that both compounds bear promising potential for discovering new anti-biofilm and quorum quenching agents against Pseudomonas aeruginosa without triggering resistance mechanisms as the normal bacterial life cycle is not disturbed.

Recent developments in the synthesis of hybrid antimalarial drug discovery

In this 21st century, Malaria remains a global burden and causes massive economic trouble to disease-endemic nations. The control and eradication of malaria is a major challenge that requires an urgent need to develop novel antimalarial drugs. To overcome the aforementioned situation, several researchers have given significant effort to develop hybrid antimalarial agents in the search for new antimalarial drugs. Hence, we have summarized those developments of hybrid antimalarial agents from 2017 to till date. This review illustrates the current progress in the recent synthesis of hybrid antimalarial agents along with focusing on their antimalarial evaluation to find the most potent hybrids. This present mini-review will also be useful for the scientific community for the development of new antimalarial drugs to eradicate malaria.

Is structural hybridization invoking new dimensions for antimalarial drug discovery research?

Despite effective prevention methods, malaria is a devastating, persistent infection caused by protozoal parasites that result in nearly half a million fatalities annually. Any progress made thus far in the eradication of the disease is jeopardized by the expansion of malaria parasites that have evolved to become resistant to a wide range of drugs, including first-line therapy. To surmount this significant obstacle, it is necessary to develop newly synthesized drugs with multiple modes of action that may have a novel target in various stages of Plasmodium parasite development and this is made possible by the hybridization concept. Hybridization is the combination of at least two diverse pharmacophore units with some linkers bringing about a single molecule with a diverse mode of action. It intensifies a drug's physiological and chemical characteristics, such as absorption, cellular target contact, metabolism, excretion, distribution, and toxicity. This review article outlines the currently published most potent hybrid drugs against the Plasmodium species.

Development of diphenylmethylpiperazine hybrids of chloroquinoline and triazolopyrimidine using Petasis reaction as new cysteine proteases inhibitors for malaria therapeutics

Malaria is a widespread infectious disease, causing nearly 247 million cases in 2021. The absence of a broadly effective vaccine and rapidly decreasing effectiveness of most of the currently used antimalarials are the major challenges to malaria eradication efforts. To design and develop novel antimalarials, we synthesized a series of 4,7-dichloroquinoline and methyltriazolopyrimidine analogues using a multi-component Petasis reaction. The synthesized molecules (11-31) were screened for in-vitro antimalarial activity against drug-sensitive and drug-resistant strains of Plasmodium falciparum with an IC₅₀ value of 0.53 μM. The selected compounds were screened to evaluate in-vitro and in-silico enzyme inhibition efficacy against two cysteine proteases, PfFP2 and PfFP3. The compounds 15 and 17 inhibited PfFP2 with an IC₅₀ = 3.5 and 4.8 μM, respectively and PfFP3 with an IC₅₀ = 4.9 and 4.7 μM, respectively. Compounds 15 and 17 were found equipotent against the Pf3D7 strain with an IC₅₀ value of 0.74 μM, whereas both were displayed IC₅₀ values of 1.05 μM and 1.24 μM for the PfW2 strain, respectively. Investigation of effect of compounds on parasite development demonstrated that compounds were able to arrest the growth of the parasites at trophozoite stage. The selected compounds were screened for in-vitro cytotoxicity against mammalian lines and human red-blood-cell (RBC), which demonstrated no significant cytotoxicity associated with the molecules. In addition, in silico ADME prediction and physiochemical properties supported the drug-likeness of the synthesized molecules. Thus, the results highlighted the diphenylmethylpiperazine group cast on 4,7-dichloroquinoline and methyltriazolopyrimidine using Petasis reaction may serve as models for the development of new antimalarial agents.

Quinazolinone-based hybrids with diverse biological activities: A mini-review

Quinazolinone and quinazoline have been shown different pharmacological activities, namely anticancer, anti-inflammatory, anti-hyperlipidemia, analgesic, antihypertensive, and antibacterial. On the other hand, molecular hybridization is a structural modification technique in the design of new ligands which consist of two or more pharmacologically active molecules in one structure. Therefore, due to the importance of the biological activities of quinazolinones for the development of new therapeutic agents, this review emphasizes current findings on various quinazolinone-based hybrids in medicinal chemistry. Moreover, it highlights the biological activities and structure-activity relationship of these hybrids.

Recent advances in the pharmacological diversification of quinazoline/quinazolinone hybrids

Due to the pharmacological activities of quinazoline and quinazolinone scaffolds, it has aroused great interest in medicinal chemists for the development of new drugs or drug candidates. The pharmacological activities of quinazoline and its related scaffolds include anti-cancer, anti-microbial, anti-convulsant, and antihyperlipidaemia. Recently, molecular hybridization technology is used for the development of hybrid analogues with improved potency by combining two or more pharmacophores of bioactive scaffolds. The molecular hybridization of various biologically active pharmacophores with quinazoline derivatives resulted in lead compounds with multi-faceted biological activity wherein specific as well as multiple targets were involved. The present review summarizes the advances in lead compounds of quinazoline hybrids and their related heterocycles in medicinal chemistry. Moreover, the review also helps to intensify the drug development process by providing an understanding of the potential role of these hybridized pharmacophoric features in exhibiting various pharmacological activities.

Recent advances in quinazoline/quinazolinone hybrid heterocycles in medicinal chemistry and their pharmacological diversification.

Green synthesis, biological evaluation, molecular docking studies and 3D-QSAR analysis of novel phenylalanine linked quinazoline-4(3H)-one-sulphonamide hybrid entities distorting the malarial reductase activity in folate pathway

A modified Grimmel's method for N-heterocyclization of phenylalanine linked sulphonamide side arm at position-2 was optimized leading to 2,3-disustituted-4-quinazolin-(3H)-ones. Further, [Bmim][BF₄]-H2O (IL) was used as green solvent as well as catalyst for the synthesis of twenty two hybrid quinazolinone motifs (4a-4v) by N-heterocyclization reaction using microwave irradiation technique. The in vitro screening of the hybrid entities against the malarial species Plasmodium falciparum yielded five potent molecules 4l, 4n, 4r, 4t & 4u owing comparable antimalarial activity to the reference drugs. In continuation, anin silicostudy was carried out to obtain a pharmacophoric model and quantitative structure activity relationship. We also built a 3D-QSAR model to procure more information that could be applied to design new molecules with more potent Pf-DHFR inhibitory activity. The designed pharmacophore was recognized to be more potent for the selected molecules, exhibiting five pharmacophoric features. The active scaffolds were further evaluated for enzyme inhibition efficacy against alleged receptor Pf-DHFR computationally and in vitro, proving their candidature as lead dihydrofolate reductase inhibitors as well as the selectivity of the test candidates was ascertained by toxicity study against vero cells. The perception of good oral bioavailability was also proved by study of pharmacokinetic properties.

Recent Development on Importance of Heterocyclic Amides as Potential Bioactive Molecules: A Review

Background:

Heterocyclic compounds are an integral part of the chemical and life sciences and constitute a considerable quantum of the modern research that is being currently pursued throughout the world.

Methods:

This review was prepared by collecting the available literature reports on various databases and an extract was prepared for each report after thorough study and compiling the recent literature reports on heterocyclic amides from 2007 to 2018.

Results:

This review summarizes the bio-potential of heterocyclic amides as antimicrobial, anticancer, anti-tubercular and antimalarial agents which would be very promising in the field of medicinal chemistry.

Conclusion:

A wide variety of heterocyclic amides have already been reported and some are currently being used as active medicaments for the treatment of disease. Still, the research groups are focusing on the development of newer heterocyclic amide derivatives with better efficacy, potency and lesser side effects. This area has got the tremendous potential to come up with new chemical entities of medicinal importance.